the object to this thread is to make a some what of a check list of everything that can / has caused a idle issues/ surge and a mis fire...

i dont need the entire story, just what fixed the issue

i have noticed latly there is a asssss load of threads about mis/rough idle. 80% of the time people jump to opti's. I personally dont think the opti is the root of all problems, ya its a pita but a well taken care of opti will last years.

please post something you have fixed,or have had fixed....not something you have read and you think can cause a mis or rough idle.

IF you post something general like a vacuume line, please explain what line it was...

i will start.

spark plugs(crossed wire and or bad wires)
bad sparks & incorrectly gapped sparks (0.50 fyi)
ICM
Vaccuum (the line that comes from the front of the TB to the side of the head)opti
opti harness
fuel pump
fuel filter
coil

Of course several overlaps with your list -Wolf, but I notice no mention yet here of intake manifold leaks. That's so obvious (and gotta be real common on a 15 year old iron motor) that I guess I always overlook it.

In my case the previous owner had a mechanic tune up the car, new plugs and wires. ran rough and missed on one cylinder. One plug on the passenger side was loose, had oil on the threads and would not make a good ground. New plugs took care of it.

My experience:
1. Ignition coil was shorting internally, making a tic noise every time it fired that was tied to engine RPM. The car ran noticeably better and started quicker with a new coil.
2. Fuel injectors can and do partially fail. My wagon had run hot for awhile and was poorly maintained. I sent the injectors to Witchhunter performance and they found 2 or 3 injectors that flowed at around 60% of capacity with an awful spray pattern. One was also not opening in time so we had to junk that one. It costs around $17 apiece to have an injector tested and cleaned. Cheaper than a tuneup.
3. The #7 spark plug wire will short on the frame or brakelines when wet if you don't run it in the factory loom, or build a plastic/rubber insulated holder assembly. If you tie it to the frame or brakelines, leave enough slack for the movement of the motor relative to those components, otherwise the motor will pull that wire off when you rev it.

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